Replicating IBM SLT/MST card interconnect

Tom Stepleton stepleton at
Sun Aug 22 10:31:13 CDT 2021

There wasn't much advice to be had on making modern connectors that
interoperate with the header-like connectors used by IBM SLT cards, so I
did my best to come up with some on my own. This design appears to be
functional, but I've only ohmed it out so far, not put it to any kind of
extended use:

The hard part now will be getting my hands on 18 AWG flat ribbon cable that
doesn't cost a fortune.

Anyhow, I hope this might be of use to some folks out there.

On Thu, Jul 29, 2021 at 1:21 PM Tom Stepleton <stepleton at> wrote:

> Hi cctalk,
> I'm looking to replicate the 24-contact connector system that IBM used on
> SLT and MST cards for many years. Has anyone done this before?
> The best photos of this connector that I can find online are on this page:
> I haven't searched Bitsavers documentation extensively for IBM
> specifications, but I've seen some details around page 54 of this document:
> I'm interested in reproducing both polarities of this connector: plug and
> socket. Also, even though the most familiar use of this connector is for
> board-to-board interconnect, I'm most interested in wire-to-board
> interconnect. IBM used this method for DC power connectors in its  5100,
> 5110, and 5120 computers. Here are images of this specific connector:
> taken as still images from a YouTube video on the IBM 5120 by Jerry Walker
> (
> I've designed and built a device that monitors DC power supply voltages
> for overvoltage and undervoltage excursions and cuts off all power rails if
> any voltage goes out of spec. I hope to use it to protect my own IBM 5100
> from major power supply faults like the one CuriousMarc encountered with
> his 9825T:
> In order to put my device between my 5100's power supply and the logic
> card backplane, I need to recreate a plug and a socket so that I can
> fashion a cable that goes out to my device. If anyone has created
> dependable modern versions of these connectors, would you mind sharing any
> pointers?
> Thanks for any help,
> --Tom

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